Equipment for preparing underground drifts, e.g. tunnels, channels, shafts, etc.

ABSTRACT

The invention relates to equipment for producing underground drifts, by means of which a much bigger drift driving progress can be realized than up till now, under practically optional soil conditions and groundwater conditions and in addition without any previous drainage. The propulsion of the lining units requires less demand on force and at the same time a perfect waterproofing can be achieved between the individual lining units and between the cutting shield and the adjacent lining unit.

United States Patent 91 11 3,731,977 Benedek et al. 1 51 May 8, 1973[54] EQUIPMENT FOR PREPARING [56] References Cited UNDERGROUND DRIFTS,E.G. UNITED ES PATENTS TUNNELS, CHANNELS, SHAFTS, ETC.

2,425,169 8/1947 Wilson ..6l/85 [75] Inventors: Miklos Benedek; TamasIrsai; San- 3,379,024 4 1968 Wohlrneyer dor Fekete; Sandor Ambrus;Istvan 3,650,116 3/1972 Cunningham ..61/85 Savolyi; Zoltan Both, all ofBudapest, Hungary Primary Examiner-Dennis L. Taylor [73] Assignee:Banyaszati Tervezo Intezet, Bu- Attorney-Young & Thompson dapest Hungary57 1 ABSTRACT [22] Flled: 1971 The invention relates to equipment forproducing un- [21] Appl. No.: 119,227 derground drifts, by means ofwhich a much bigger drift driving ro ress can be realized than u tillnow,

d ll l l d d d un er practica y optiona soi con itions an groun [52]U.S. Cl. ..299/31, 6l/42,2691;/8657, water Conditions and in additionwithout y previous [51] Int Cl End 9/00 drainage. The propulsion of thelining units requires [58] Fieid less demand on force and at the sametime a perfect waterproofing can be achieved between the individuallining units and between the cutting shield and the adjacent liningunit.

7 Claims, 8 Drawing Figures PATENTED HAY 81875 SHEETBUFd' EQUIPMENT FORPREPARING UNDERGROUND DRIFTS, E.G. TUNNELS, CHANNELS, SHAFTS, ETC.

The invention is equipment for preparing underground drifts, e.g.,tunnels, channels, shafts, etc.,

where the process is performed by means of cutting shield provided withbreaker equipment, of a row of protecting units to support the driftsalready excavated, of devices to perform the jacking-operation, as wellas of a conveying system to remove the muck out of the drift.

One has delt with the construction of underground lineal drifts, so oftunnels, channels, mine roadways, etc., since a very long time. Formerlythese were built in drifts shaped with hand tools and protected withwooden propping (timber work). In case of engineering structures oftunnel character their cross section was formed mainly with archedlining. The so called tubing structures made of steel and reinforcedconcrete respectively, which are constructed by means of protectingshield, appeared at the end of the 19th century and became general inthe th century. The characteristic feature of both the mining and theshield construction technology is the continuous building with smallsize segments, the use of jacking technology at the lineal structuresstarted after the 2nd World War, at first with relatively shorter tubesof small diameter, then later on with bigger and longer tubes.

The jacking generally has begun from a vertical shaft or working pit, bymeans of a hydraulic ram system. The methods known today enable thejacking of pipes of several meter lengths and of 2 to 3 meter diametermade of reinforced concrete, plastic material or steel, up to a maximumcontinuous length of 40 to 60 meters. After every continuous sectionanother intermediate jacking-station and working pit has to be arrangedrespectively, where the ram-system necessary for jacking the nextsection, will be placed. One of the numberous known equipment used forsuch purpose is the Westfalia-Liinen-system.

In spite of their general use, the known shield-driving and pipe-jackingmethods have several drawbacks. Most important of them, as mentioned byK. Szchy in its book The Art of Tunneling, that they can operatetrouble-free and with a good efficiency only in grounds which arehomogeneous in the total length. If the soilcharacteristics change orthe ground contains boulders, wet sand pickets etc., their operation isno more satisfactory. In such a case repeated mechanic readjusting isnecessary which causes significant loss of time.

A disadvantage of the known mechanic equipment is that they by no meansor only partly prop the face and cannot prevent the groundwater fromseeping trough the face. The mechanic break is unsolved in case ofwaterlogged, granular and plastic clay soils. These disadvantagesequally concern the rotor-, cutting disc-, hemispherical cutting headandbucket excavator equipment and their combinations.

Similarly disadvantageous is the construction technology itself, whichis coupled with the equipment, mainly therefore, since the waterproofingis not solved satisfactorily at the place of the rams propulsioning thelining segments, and so the methods can well and efficiently appliedonly under favorable groundwater conditions. It is disadvantageous toothat the move of the pipe-shaped protecting units which form at the sametime the cross section of the tunnel cannot be performed continuously,but in periodical strukes in consequence of which the jacking itselfrequires very great forces.

The ram-system arranged at a distance of 40 to 60 meters, exerting greatforces, naturally give very great axial load onto the pipes. As aconsequence, it is often experienced that e.g., units made of steelundergo damaging deformations and the ends of the concrete blocksmoulder, which still makes worse the waterproofing at the joints.

A peculiar drawback of the known processes and equipment that owing tothe nature of the jacking move, they practically can be used only forproducing engineering structures driven is straight line, while theshaping of tunnels curved horizontally or vertically can be performed byno means or only extremely circuituously.

The aim of the invention is to provide equipment for producingunderground drifts, by means of which a much bigger drift drivingprogress can be realized than up till now, under practically optionalsoil conditions and discretional groundwater conditions, and inaddition, without any previous drainage. Besides, task of the inventionis too that the propulsion of the lining units should require lessdemand on force, and at the same time, perfect waterproofing is to beachieved between the individual lining units, and between cutting shieldand near by lining unit respectively.

Basic idea of the invention is the perception that such units can beshaped of tire-like rubber-rings for waterproofing between the units,which, because of their tire-like form, can be placed under pressure,and by means of the pressure they can be forced to such deformations,with the help of which the rubber ele ments can display great tensileforces. In otherwords this means that instead of the conventionalconstruction technology based on the jacking, we can realize anotherconstruction technology performing worming caterpillar-like movement,"which is characterized by that the lining units are moved not bycompressive-, but by pull forces. This ensures a practically continuousmoving and also advancing along an optimal trace.

Basic difference is, compaired with the traditional shield-driving andpipe-jacking technology that the advancing takes place thereperiodically and in long strokes (30 to 60 cms) produced by hydraulicrams, whereas according to the method proposed by us, the advancingtakes place in shorter (l to 10 cms) strokes" as a consequence of thenature of the tensile units. Though this advancing takes place locallyat various places, the row of units taken as a whole, moves essentiallycontinuously.

Equipment according to the invention, to prepare underground drifts,e.g., tunnels, channels, shafts, etc.,

which equipment possesses cutting shield provided with breakerequipment, row of protecting units for supporting the shaped drift,devices for the jacking operation, as well as a transporting system forremove the excavated material out of the drift, characterized by thatthe cutting shield consists of cutting edge part the elements of whichare connected movable in relation to each another, shield trunk andshield tail part, in the cutting shield there is a waterproofbucket-ladder breaker equipment moved by propulsion and turn, thecutting shield as locomotive" together with the row or protecting unitscoupled behind it as row of cars," and with the elastic tensile elementsinserted between the members of the row of protecting units is composedas train" suitable for gradually advancing move.

As to the mechanical equipment its main advantage is that the cuttingshield assembled specially and the breaker equipment units all favorableproperties of the mechanic shield known up till now and of the shieldtypes of closed face respectively. Most decisive of them is that it canbe applied in whatever type of ground without any technologicalalteration, requires neither previous drainage nor internaloverpressure, the face is propped up by the cutting crown and itprovides security against slackening or breaking in of the roof.

Particularly advantageous is, compared with the known equipment that anaccurate rock section can be broken, it is not necessary to applydividing platforms and face closing elements even in case of largesections, it is easy to ensure the direction control while advancing andthe precise adjusting to a discretional trace respectively. Regardingthe operation, it is remarkable that weight, costs and energy demand ofthe equipment is much less than those of the solutions known up tillnow, and at the same time, the handling of the equipment is essentiallymore simple too.

The enumerated advantages are insured by the circumstance that thecutting shield of the equipment is such a rigid steel constructionconsisting of three partsthe cutting edge part, shield trunk and shieldtail part the members of which can be move in axial direction ascompared to each another, however, perfect water-proofing is insuredbetween the members, while propulsioning the cutting shield by one onlybigger stroke, it is supported by the row of protecting units beingbehind it, and conversely, while moving forward the row of protectingunits by smaler strokes, the cutting shield ensures the hold in thedrift. This latter can take place by means of leaning elements extendingfrom the shield trunk, by means of which the cutting shield is able tofix itself in whatever ground.

The good efficiency of the equipment is enabled by the special breakerequipment, a dredger, the bucketladder of which turns around thetheoretical longitudinal axis of the shiled and at the same time it canbe pushed forward. The dredging by buckets is suitable for the break ofall kinds of soils which practically can be met with, from thequick-sand, silt, through the waterlogged gravel, clay-sorts ofdifferent water-content and properties, detrital filling, up to the marlstill hackable without blast. The progress can be unsured nearly withoutany alteration even in soilsorts changing most capriciously. Thebuckets-ladder dredger are fitted onto links or closed chain tracktcarpet. So the cutting shield props up the face while hacking at thesame time the closed break equipment, being sealed compared to theshield, can prevent the groundwater from flowing in, by means of theclosed chain track carpet.

The invention is described in details hereunder with reference to anembodiment by way of example. On the enclosed drawing:

FIG. 1 indicates the diagrammatic layout of the equipment,

FIG. 2 shows the schematic longitudinal profile of the equipmentaccording to the invention,

FIG. 3 is the front view on the line IIIIII in FIG. 2,

FIG. 4 is a cross-section along the plane IV-IV in FIG. 2,

FIG. 5 is the schematic cross-section of the tensile element and theprotecting-waterproofing element, and FIGS. 6A and 6B are enlargedfragments of FIG. 2.

Main structural members of equipment according to the invention toprepare underground drifts are: A cutting shield B breaker equipment, Crow protecting units, D tensile elements and E protecting-waterproofingelements. Part of A cutting shield are: A, cutting edge part, A, shieldtrunk and A shield tail part, members of B breaker equipment are: B,mining drum, B actuating system and B transporting equipment.

Within A, cutting edge part the most important structural details: 1cutting crown, 2 carrier ring, 3 actuating cylinders for pushing forwardA, cutting edge part, 4 actuating cylinders for moving B, mining drum,as well as B breaker equipment itself, which is mostly placed in theinterior of A, cutting edge part. Both the 3, 4 actuating cylinders andthe B breaker equipment partly extend into the A shield trunk.Incidentally, the A shield trunk is provided with 6 leaning elementsserving for propping up, and 7 actuating cylinders for wedging these inradial direction, respectively, 5 actuating cylinders to ensure thepushing forward of the whole A shield trunk, being placed however mostlyin A shield tail part.

The 8 end plate is placed on the side of B, mining drum of B breakerequipment which is facing towards the drift-face. The 8 end plate is acomponent part of 9 closed box including the b breaker equipment. Theactuating part of B breaker equipment is the endless chain assembled of10 closed links and 11 open links respectively, on which the 12 dredgingbuckets are fitted to prop up the face. This endless chain is threadedover 13 angle sheave and 14 roller, guided in 15 way and its rotation isinsured by 16 actuating reeler.

A indicated on FIG. 3, the 17 tangential knife discs are situated along8 end plate, as well as 18 radial knife discs embedded radially novable,which, in addition to 12 dredging buckets, also serve for attacking theface. The 19 gear rim is placed on the internal side of 2 carrier ringto ensure the spatial stiffness of A, cutting edge part, which thetoothed wheels of the drive fixed into B, mining drum clutch at.Similary, the 20 pressure distribu ting ring in the rear part of A,cutting edge part the 2] pressure distributing ring in A shield trunkand the 22 pressure distributing ring between A shield trunk and Ashield tail part, as well as 23 pressure distributing ring in the rearpart of A shield tail part, serve for spatial stiffening of the Acutting shield too, but at the same time they also serve for taking,dividing unformly and transmitting respectively the forces exerted bythe jacking-systems possessing 3,4 and 5 actuating cylinders.

By the method indicated on FIG. 3., a 24 opening is formed on the 8 endplate of B breaker equipment, through which the break can be performedon the face by 12 dredging bucket provided with 25 cutting edge. In thecourse of the hacking operation the B, mining drum has to be able toturn around its 26 theoretical longitudinal axis (which otherwisecoincides in this case with the theoretical axis of the whole A cuttingshield), to which the possibility is given by 27 ball rim embedding theB, mining drum in the A, cutting edge part, and the sliding bednecessary for pushing forward B, mining drum is provided by 28 slipper.The turning of the mining drum B, will be suspended during each dredgingphase, then, when the sum of the gradual turns amounts to nearly 180,the mining drum B, will be propulsioned and the sense of the gradualturns will be changed. The muck hacked by B, mining drum is dischargedby 12 dredging buckets onto the 29 drag conveyor forming a part of Btransporting equipment. The B, mining drum, as can be seen on FIG. 2(marked with dotted line), can be extended before the face of 1 cuttingcrown by means of axial moving on 28 slipper. B, mining drum can work insuch a position if the A cutting shield advances in stable ground. It isto be remarked that in such a case possibility is given too that theendless chain rotating the 12 dredging buckets should consist 11 openlinks only. When advancing in running or loose soil layer, B, miningdrum can be drawn back behind the face-plane of 1 cutting crown, and insuch a case the part of the 1 cutting crown that falls into thelengtheing of 30 skin of A, cutting edge part umbrella-like the 8 endplate B, mining drum, and the 12 dredging buckets appearing periodicallyin the 24 opening respectively, against breaking in of the loose ground.Naturally, in case of such soils, the endless chain rotating the 12dredging buckets must prevailingly consists of 10 closed links as aclosed chain track carpet, only one or two 10 closed links before the 12dredging buckets are substituted by U open links. In this case eitherthe gradual turn of the mining drum B or the gradual turn of the miningdrum B, and the operation of the dredging buckets 12 will besimultaneously suspended, and in this latter case the material to bemined can only flow from the face into the interior of the mining drum.We insure waterproofing between the inner skin-surface 30 of the cuttingedge part A, and the mining drum B, and the moisture seeping on throughthe end plate 8 of the mining drum B,which can be closed in a variabledegree will be removed from the mining drum B, through the normaldischarging place of the stripped muck. Between A, shield trunk andshield tail part, as well as between A, cutting edge part and A, shieldtrunk part are placed the 31 elastic waterproof connections, whichinsure that the internal place within the A cutting shield should be drypractically, even if the work is performed under the water-table. Thesame waterproofing function is ensured between the members of the row ofprotecting units by the D tensile elements and the Eprotecting-waterproofing elements respectively. The D tensile elementsare tires, which can be pumped up with gaseous material or may be filledup by liquid material, and which are joined with the two neughboringprotecting units by 32 peripheric flanges, and are provided withconnecting stubs insuring filling up and discharging respectively.

By means of process according to the invention and with the use ofequipment outlined above, the preparation of underground drifts takesplace as follows.

First of all some kind of starting room, e.g., shaft is to be prepared,starting of which, protecting units suitably of ring or othercross-section are to be addedto, always from behind, considering theprogress direction along the trace. Inthe course of this the train,consisting of A cutting shield, as well as of some protecting unitsjoining to it, is propulsioned, being supported in the starting shaftsfirst. This part of the operation is similar to the traditionalshield-jacking construction technology. However these initial steps arenecessitated only until the friction force between the advanced Acutting shield and members of the row'of C protecting units alreadymounted behind it and the surface of the rock section is great enough toinsure the locomotivity of the train. From that moment on that the trainbecame locomotive in this manner, on one hand the supporting in thestarting shaft will be unnecessary, on the other hand the C row ofprotecting units already placed advances by pulling, due to the powereffects transmitted by the D tensile elements.

Though the A cutting shield will be propulsioned by jacking afterreaching the locomotivity, however so that the necessary supportingforce comes into being by skin friction of the protecting units of nnumber already placed. The movement is then continuous, and is made upactually of two cycles, namely the moving forward of A cutting shield bypushing force, further the moving period of C row of protecting units bypulling force. Within this we have to mention that the movements of A,cutting edge part, A shield trunk and A shield tail part of A cuttingshield do not take place simultaneously and in one phase. Namely, in thefirst phase the A, cutting edge part of A cutting shield is pushedforward onto the A shield trunk by one only H stroke by means of the 3actuating cylinders propped up by the A shield tail part, as well as bythe C row of protecting units already built in. The H stroke is ofdm-order, in extreme case it can be even about I m. After finishing theadvancing of A, cutting edge part, the elements increasing the frictionof A, shield trunk in case of the referred embodiment of an example the6 leaning elements are drown in, hereby rendering possible that the A,cutting edge part could be easily followed by the A shield trunk. Thepower necessary to perform this movement is supplied by the ram-systemconsisting of 5 actuating cylinders placed in the A shield tail part,which pushes forward in this manner the A shield trunk supported by theA shield tail part, as well as by.

8-10 cm). This moving in parts takes place by means of controlautomation known for itself. Regarding its character, this gradualpropulsion in small steps is similar to stringing of beads, while thecommon movement of A cutting shield and C row of protecting units can beactually considered as worming caterpillar-like movement in that waythat alternatively either one part of it is stationary while the otherone moves or the other way round. The move rate of A cutting shield andC row protecting units is determined by the I-I/h ratio.

Trains of optional length could be theoretically composed by thismethod, this is, in other words, by means of one only starting shaft anunderground drift of discretional length and trace could be prepared.Practically the uninterrupted length is limited by the circumstance thatboth the energy demand necessary for the moving and the transportationlength of the muck increase proportionally with the length of C row ofprotecting units. In addition, the increasing length of the driftalready prepared causes special worry regarding ventilation too.

Because of the above considerations it is expedient to interrupt themovement of the train by arranging further starting shafts at a spacingof some hindred meters. This is performed so that after having the Acutting shield passed the intermediate shaft, the detachment of the Crow of protecting units will be carried out only when the A cuttingshield has already advanced to a distance from the intermediate shaftthat the skin friction between A cutting shield and shaft, necessary forself-propelling the train, is at disposal again along the C row ofprotecting units being on this section. This method is especiallyexpedient, since in such a case the intermediate shafts are not to beprovided with supporting structure, for the members of C row ofprotecting units have not to be propulsioned by jacking not even uptothe self-propelling is achieved. Naturally, after the separation takenplace at the intermediate shaft, the section of row of protecting unitsbeing before the intermediate shaft ceases to move the drift alreadyprepared. So the actuating energy can be used more economically.Similary saving move energy is aimed at by the measure that after havingplaced n pieces of protecting units sufficient to insure theselfpropelling of the train, i.e., to support A cutting shield,thixotrope fluid is brought in between the external surface of thefurther members of C row of protecting units and the surface of the rocksection, with the use of which the skin friction can be decreased. So,the haulage of this steadily increasing section of the train will bepossible with less energy too.

One of the main guarantees of the success of process is the suitableforming and operation of D tensile elements placed in between themembers of C row of protecting units. According to the examinations, itis expedient to use rubber or synthetic material tire for this purpose,the end of which are fixed expediently to the members of C row ofprotecting units by fittings of steel structure. In the case of theembodiment of the example, the D tensile elements are operated bycompressed air. When pumping up, the tensile elements being originallyof flat cross section in axial direction, endeavor to take oviform crosssection, as a consequence of pumping, while they pull the followingprotecting unit to the unit before them, in particular always with adistance of a stroke ofh size. The value of pulling force that can beproduced by D tensile elements depends on the pressure of the fillingmedium and naturally, on the geometrical data of the D tensile elementitself. According to examinations, to Mp/running meter force measuredalong the circumference of the row of protecting units, can beconsidered as optimum to haul the row of units. It is to be remarkedthat the D tensile elements insure a waterproofness between theneighboring members of the protecting units.

The D tensile elements are supplied with E waterproofing elements too,which provide that no groundwater and soil grains can get in between theD tensile elements and the fittings fixing them to the protecting units.The E protecting-waterproofing elements are elastic rings of bell-shapedcross section, as can be seen on FIG. 5., made of rubber or syntheticmaterial, which can follow the deformation of the D tensile elements. Atthe same time, the D tensile elements and E protecting-waterproofingelements are also suitable, that the distance between the end faces ofthe members of C row of protecting units and the relative position ofthe neighboring members of the protecting units compared with eachanother respectively, could be changed, and so, in case of advancing incurve the protecting unitmembers can adjust themselves along thechordpolygon, osculating to the curved trace.

We should like to mention that though the 8 end plate of the breakerequipment placed in the A, cutting edge part is closed, and the 24opening being on it, necessary for breaking, is covered by the chaintrack carpet consisting of 10 closed links, and is sealed even in caseof work to be performed under the groundwater-table, however, certainseepage can occur between its parts joining to each another. The upperopening, necessary for introducing the 25 cutting edge of 12 dredgingbucket, can be covered by the 25 cutting edge itself, and the bottomopening can be covered by an eventual 33 spring cover plate. Only aminimum seepage can occur between them too. Otherwise it is necessary toclose the 24 opening of 8 end plate by means of 12 dredging bucket only,if the ground is inclined to flow even without artificial breaking, fromthe face into B mining drum. This occurs in case of uncoherent, quicksubsoils. Otherwise the water percolating into the B breaker equipmentcan leave the B mining drum only concentrated, at the normal dischargingplace of the 12 dredging bucket, and it can be pumped off from here incase of necessity.

The process and equipment according to the invention, apart fromconstructing underground channels and tunnels respectively, istheoretically suitable to sink whatever kind of inclined shafts, inextreme case even vertical ones, and compared with the methods known uptill now, it is quicker, more economic and of greater efficiency.

We claim:

1. In underground mining machinery comprising a cutting shieldencompassing power-driven digging members, a series of protecting unitsfor supporting the earth to the rear of the digging members and conveyormeans for conveying earth rearwardly from the digging members withinsaid supporting units; the improvement in which the cutting shieldcomprises a cutting edge, a shield trunk, and a shield tail, fluidpressure cylinder and piston assemblies interconnecting said cuttingedge and shield trunk for longitudinal movement relative to each other,fluid pressure cylinder and piston assemblies interconnecting saidshield trunk and shield tail for longitudinal movement relative to eachother, said digging members comprising a plurality of buckets on anendless circulating member, power means for circulating said endlessmember, said sup porting units being in the form of a longitudinallyextending series, elastic tensile means interconnecting the members ofsaid series, and elastic waterproof means interconnecting the members ofsaid series in fluidtight relationship.

2. Mining machinery as claimed in claim 1, said shield trunk comprisingrelatively movable elements in a peripheral series about said shieldtrunk, and means for moving the members of said peripheral seriesradially outwardly.

3. Mining machinery as claimed in claim 1, said digging members beingdisposed in a box which is closed by a plate in the direction ofmovement of the mining machinery, said plate having an opening throughwhich said digging members protrude, and means sealing between saidendless circulating member and said plate.

4. Mining machinery as claimed in claim 1, and means to advance androtate said endless circulating member relative to said cutting shield.

5. Mining machinery as claimed in claim 4, and cutting discs whose axesare disposed radially of the longitudinal axis of the mining machinery,and means to advance said discs and to rotate said discs about said

1. In underground mining machinery comprising a cutting shieldencompassing power-driven digging members, a series of protecting unitsfor supporting the earth to the rear of the digging members and conveyormeans for conveying earth rearwardly from the digging members withinsaid supporting units; the improvement in which the cutting shieldcomprises a cutting edge, a shield trunk, and a shield tail, fluidpressure cylinder and piston assemblies interconnecting said cuttingedge and shield trunk for longitudinal movement relative to each other,fluid pressure cylinder and piston assemblies interconnecting saidshield trunk and shield tail for longitudinal movement relative to eachother, said digging members comprising a plurality of buckets on anendless circulating member, power means for circulating said endlessmember, said supporting units being in the form of a longitudinallyextending series, elastic tensile means interconnecting the members ofsaid series, and elastic waterproof means interconnecting the members ofsaid series in fluidtight relationship.
 2. Mining machinery as claimedin claim 1, said shield trunk comprising relatively movable elements ina peripheral series about said shield trunk, and means for moving themembers of said peripheral series radially outwardly.
 3. Miningmachinery as claimed in claim 1, said digging members being disposed ina box which is closed by a plate in the direction of movement of themining machinery, said plate having an opening through which saiddigging members protrude, and means sealing between said endlesscirculating member and said plate.
 4. Mining machinery as claimed inclaim 1, and means to advance and rotate said endless circulating memberrelative to said cutting shield.
 5. Mining machinery as claimed in claim4, and cutting discs whose axes are disposed radially of thelongitudinal axis of the mining machinery, and means to advance saiddiscs and to rotate said discs about said axis.
 6. Mining machinery asclaimed in claim 1, said elastic tensile means comprising inflatablemembers peripherally interconnected between said protecting units, andmeans for inflating said inflatable members. 7 Mining machinery asclaimed in claim 1, said elastic waterproof means comprising annularstrips interconnected along their edges to adjacent said protectingunits.